Bad Video Quality on overlay screen

So While monitoring seabed survey our main flying overlay screen picture quality was getting bad and overlay also started giving garbage values as luckily as we had lot of time before starting project so we decided to recover and our first suspicion was overlay card so replaced with a new one and bang on overlay was back and we started dive again and 40 minutes we had same problem again of video quality going bad to worse that we were not able to fly using overlay screen at the same time so time to recover again and now its not the card and also the another factor was time as video quality was only going bad after 30-40 minutes it means either power supply supplying the overlay circuit is getting heat up and dropping voltage so there might be a chance that there is not enough cooling in Surface unit or our LASCAR Power supply#1 has gone bad.

We started with replacing power supply and problem was solved,

So this problem which was time bound and occurs after a certain period check for cooling or power supply itself.

Hope this small experience of mine which i hope will help some of you.